The invention relates to sealing structures between a rotating component and a static component typically found in turbomachinery and, more particularly, to a compliant-plate seal arrangement including staggered shingles that are effective in reducing axial leakage.
Dynamic sealing between a rotor (e.g., rotating shaft) and a stator (e.g., static shell, casing or housing) is an important concern in turbomachinery. Several methods of sealing have been proposed in the past. In particular, sealing based on flexible members has been utilized including seals described as leaf seals, brush seals, finger seals, shim seals, etc.
A brush seal is comprised of tightly packed generally cylindrical bristles that are effective in preventing leakage because of their staggered arrangement. The bristles have a low radial stiffness that allows them to move out of the way in the event of a rotor excursion while maintaining a tight clearance during steady state operation. Brush seals, however, are effective only up to a certain pressure differential across the seal. Because of the generally cylindrical geometry of the bristles, the brush seals tend to have a low stiffness in the axial direction, which limits the maximum operable pressure differential to generally less than 1000 psi. Radial and axial directions in this context are defined with respect to the turbo-machine axis.
To overcome this problem, leaf seals have been proposed that include a plate-like geometry with higher axial stiffness and therefore the capability of handling large pressure differentials. Axial leakage, however, remains a problem due to the leaf seal geometry. That is, with reference to FIG. 1, if the uniform-thickness leaves L are packaged tightly close to the rotor R, there will be gaps G at the leaf roots, which potentially cause leakage and in turn can offset the benefits of the seal.